Embodiments of the present invention relate to a composition for etching silicon oxide and a method of forming a contact hole using the same. More particularly, in embodiments of the present invention relate to a composition for etching silicon oxide, which may be used for enlarging a hole formed in a silicon oxide layer and a method of forming a contact hole using the composition.
In order to proceed with a large quantity of information more rapidly, a semiconductor device having a high transmission rate of data is required. Accordingly, the integration degree of a cell included in the semiconductor device has increased, but a design rule of the wiring has decreased. As the design rule has been reduced, the wiring of the semiconductor device has been developed to have a three dimensional shape or a multi-layered structure. The integration degree of the semiconductor device is increased in reverse proportion to a gap between conductive patterns. It also increases in proportion to the occurrence probability of a misalignment of the conductive patterns during a photolithography process that may be performed for forming a contact hold through an insulation interlayer between the conductive patterns.
Furthermore, when the design rule of the wiring is decreased down to about 80 nm, the width of the contact hole which penetrates the insulation interlayer between conductive structures, such as a bit line, and exposes a contact pad which is also reduced greatly. As a result, an exposed area of the contact pad becomes very limited, and thus a contact margin between a contact plug formed in the contact hole and the contact pad may be insufficient.
The width of the contact hole may be enlarged by using an etching solution such as an LAL 200 solution including hydrofluoric acid and ammonium fluoride so as to obtain a sufficient contact margin between the contact plug for the capacitor and the contact pad.
However, the etching solution such as an LAL 200 solution employed for enlarging the contact hole has a high etching rate with respect to the metal silicide pattern included in the conductive structure. Therefore, as shown in a portion “C” in FIG. 1, excessive damage to the metal silicide pattern may be generated. When a nitride is deposited in the contact hole in a subsequent process, the nitride fills the damaged portion of the metal silicide, thereby causing an increase of resistance in the conductive structures such as a bit line.